Notebook computers conventionally operate on either line power or battery power. When operating on battery power, the battery discharges over time until it is unable to provide sufficient power to run the notebook computer. This discharge time is referred to as the battery life. In designing notebook computers, there is a tradeoff between size of battery for increased battery life and the size and weight of the notebook computer.
Although there have been many advances in battery technology over the years, longer battery life is generally provided by increasing the number of cells in the battery. This increases both the weight and size of the notebook computer.
To provide flexible battery operation, many manufacturers offer high capacity batteries in addition to lower capacity, internal batteries. For some notebook computers, the high capacity batteries connect to the bottom of the notebook computer while others fit in the space of the lower capacity battery and extend outside the notebook computer's normal profile. When extended battery life is not needed, the high capacity battery can be removed and replaced with the lower capacity battery. Higher capacity batteries typically have more cells than the notebook's internal battery. This also means that the battery has a larger profile compared to the lower capacity battery.
Unfortunately, notebook computers often cannot dock in docking stations when an external high capacity battery is connected to the notebook computer because the battery interferes with the interface between the notebook computer and the docking station. Convenience-minded users have found this unacceptable. Some manufacturers have attempted to address this problem by modifying the design of their docking stations. These modifications are often implemented at the expense of the ergonomic layout of the docking station and/or additional equipment and cost. Further, some solutions introduce other problems such as reduced heat dissipation and the like.